1. Field of the Invention
The present invention relates to sealing plugs and more particularly to a plug assembly preshaped to create a partial interference fit with a bore to be sealed for holding the plug parts against rotation while the expansion screw is tightened.
2. Description of the Prior Art
Sealing plugs have long been known in many different designs of varying complexity, with a simple and widely used form comprising a sleeve insert having a tapered inner surface and a correspondingly tapered locking member to be driven into the sleeve to expand the latter radially into sealing engagement with the passage. Various means have been used for forcing the locking member into the sleeve, including an expansion screw threaded into the locking member. During the threading of the expansion screw into the locking member, the locking member as well as the sleeve member must be restrained against rotation, this being accomplished by means of suitable tools or by accurately sizing the sleeve to have a force fit in the passage. These arrangements for so restraining the plug assembly are relatively complicated and expensive.
Some examples of prior art arrangements are shown in U.S. Pat. Nos. 2,062,519; 2,141,274; 2,836,918; 2,856,963; 2,923,323; 3,156,373; 3,333,724; 3,525,365; 3,893,487; 4,140,040 and 4,170,247.